There is the technology of performing, in a power converting apparatus which is not provided with power storing means in a DC link unit between a converter and an inverter thereof, commutation of the converter side in a zero voltage vector period on the inverter side. That is, in the period when the inverter outputs zero voltage by a zero voltage vector, an output of the inverter is brought into a state of being short-circuited with only any one of a high potential side and a low potential side of the DC link unit, whereby current does not flow from the DC link unit to the inverter. Accordingly, in this period, input current of the converter does not flow as well, with the result that the converter is caused to perform commutation without generating loss resulting from switching.
In this technology, however, the period when the input current of the converter becomes zero is determined not by commutation of the converter, but by switching of the inverter. As a result, in a case where a single triangular wave carrier is merely used in commutation of the converter as well as switching of the inverter, in some cases, the zero vector on the inverter side affects the periods before and after the commutation of the converter in an asymmetrical manner, leading to distortion of an input current waveform.
Japanese Patent Application Laid-Open No. 2004-222337 discloses the technology for solving the aforementioned problem. In the power converting apparatus described in Japanese Patent Application Laid-Open No. 2004-222337, a peak position of a carrier on an inverter side is moved correspondingly to a ratio between ON and OFF periods of a phase in which the converter is switched, and in the ON period and OFF period of the phase, generation timing of a zero voltage period is controlled such that average current values of the DC link unit coincide with each other therebetween.
Japanese Patent Application Laid-Open No. 2004-266972 and Lixiang Wei and Thomas A. Lipo, “A novel matrix converter topology with simple commutation”, IEEE IAS 2001, vol. 3, 2001, pp. 1749-1754 and Takaharu Takeshita, Koji Toyama, Nobuyuki Matsui, “PWM scheme for current source three-phase inverters and converters”, IEEF Transactions on Industry Applications, Vol. 116, No. 1, 1996, pp. 106 and 107 disclose the technologies related to the present invention.